The invention relates to a pump with electric motor, in particular a liquid pump, wherein the electric motor comprises a rotor comprising a shaft and a magnet surrounding the shaft.
In pumps that, on the one hand, require a small size but, on the other hand, also a particularly high-performance electric motor, the rotor in practice is formed of a metal shaft or ceramic shaft and a magnet is pushed onto the shaft and then glued to the shaft. Usually, the shaft is subsequently embedded in plastic material. This configuration enables a very compact construction but the transmittable torque depends primarily on the selected adhesive connection. Also, the adhesive connections are partially subject to material fatigue so that the service life in regard to loadability is limited. In order to ensure the required connecting strength, the adhesive connection must therefore be of extremely high quality and is therefore very expensive.
It is therefore an object of the present invention to provide a pump of the aforementioned kind that, by means of the rotor construction of the electric motor, enables with beneficial conditions a high performance while providing a compact configuration of the electric motor. This is particularly relevant for pond pumps or aquarium pumps that must combine a minimal size with high performance.